Presidential tradition is to swear into office with a hand upon the Bible, end the oath of office with "So help me God" and acknowledged a Supreme Being in the Inaugural Address. Eisenhower, Reagan and George H.W. Bush also included prayers.
President Eisenhower began his Inaugural Address in 1953: "My friends, before I begin...would you permit me the privilege of uttering a little private prayer of my own. And I ask that you bow your heads. Almighty God, as we stand here at this moment..."
In 1985, Ronald Reagan began his Inaugural Address: "I wonder if we could all join in a moment of silent prayer..."
George H.W. Bush began his Inaugural Address, 1989, saying: "My first act as President is a prayer. I ask you to bow your heads. Heavenly Father, we bow our heads and thank You for Your love...Make us strong to do Your work, willing to heed and hear Your will..."
from AMERICAN MINUTE by Bill Federer at the Crosswalk website